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Re: Sorting non-standard elements

by theorbtwo (Prior)
on Oct 29, 2004 at 21:08 UTC ( #403908=note: print w/replies, xml ) Need Help??


in reply to Sorting non-standard elements

Let's start with a re-phrase. A software version consists of three numeric parts, plus any number of additional characters. The three numeric bits are sorted in numeric order, and the character bits in character order.

Here's one way to do it: Convert the human-readable version number into a cannonical form that's easy to compare. Then sort. Then convert them back into human-readable version numbers. A first attempt looks like this:

sub cannonify { my $ver = shift; $ver =~ /(\d+)\.(\d+)\.(\d+)(\w*)/ return chr($1).chr($2).chr($3).$4; } sub uncannonfiy { my $ver = shift; return ord(substr($ver, 0, 1)) . '.' . ord(substr($ver, 1, 1)) . '.' . ord(substr($ver, 2, 1)) . . substr($ver, 3); }

You will note that this isn't very efficent. Try combining it with the Schwartzian transform that other people have pointed you out, and without specifiying a comparator function to your sort call (to sort lexographicly).

Also, if you just want to find the maximum version, don't use sort, which has to do much more work, instead, use List::Util's max().


Warning: Unless otherwise stated, code is untested. Do not use without understanding. Code is posted in the hopes it is useful, but without warranty. All copyrights are relinquished into the public domain unless otherwise stated. I am not an angel. I am capable of error, and err on a fairly regular basis. If I made a mistake, please let me know (such as by replying to this node).

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